Remove unused code

Author: maskaravivek

app/src/main/java/fr/free/nrw/commons/utils/MediaDataExtractorUtil.java

@@ -8,26 +8,6 @@
 import java.util.regex.Pattern;
 
 public class MediaDataExtractorUtil {
-
-    /**
-     * We could fetch all category links from API, but we actually only want the ones
-     * directly in the page source so they're editable. In the future this may change.
-     *
-     * @param source wikitext source code
-     */
-    public static ArrayList<String> extractCategories(String source) {
-        ArrayList<String> categories = new ArrayList<>();
-        Pattern regex = Pattern.compile("\\[\\[\\s*Category\\s*:([^]]*)\\s*\\]\\]", Pattern.CASE_INSENSITIVE);
-        Matcher matcher = regex.matcher(source);
-        while (matcher.find()) {
-            String cat = matcher.group(1).trim();
-            categories.add(cat);
-        }
-
-        return categories;
-    }
-
-
     /**
      * Extracts a list of categories from | separated category string
      *